1. Field
The present invention relates to an exercise apparatus that simulates walking and running. More particularly, the present invention relates to an exercise machine having separately supported elongate pedals exhibiting programmed motion in conjunction with a collapsible frame.
2. State of the Art
The benefits of regular exercise to improve overall health, appearance and longevity are well documented in the literature. For exercise enthusiasts the search continues for a safe apparatus that provides maximum benefit in minimum time which can be stowed when not in use.
The sit down exercise cycle is the most commonly used apparatus today to elevate the heart rate and exercise some of the leg muscles. To achieve any significant benefit, however, an extensive amount of time is demanded of the user resulting in boredom. The Lifecycle, U.S. Pat. No. 4,358,105 leads a popular trend to reduce the boredom of sit down cycling by offering programmed load resistance changes over many minutes of cycling and a clever display to capture the attention of the user. However, the issue of extensive time, limited muscle usage and collapsibility for stowage are not fully addressed.
In recent years, stair climbers have become very popular due to the higher loading possible with stand-up exercise as well as different muscles used compared to sit-down cycling. The Stairmaster U.S. Pat. No. 4,708,338 is one of the most popular stairclimbers allowing up and down independent parallel foot pedal movement with programmed load variation over multiple cycles as well as a clever display to hold the attention of the user. Other stairclimbers U.S. Pat. Nos. 4,989,858 and 5,013,031 provide reciprocating foot motion but with non-parallel pedal control and differing load resistance systems.
Another group of stair climbers U.S. Pat. Nos. 4,687,195; 4,726,581 and 4,927,136 have moving stairs requiring the user to remove the foot from each stair after the down stroke. While this foot motion is more diverse than the reciprocating motion of most stair climbers, the issue of operator safety requires complex solutions for practical apparatus.
Stand-up pedaling approaches the the benefits of running to the cardiovascular system because a higher load resistance is possible over sit down cycling. Dr. Cooper in his book entitled THE AEROBICS PROGRAM FOR TOTAL WELL-BEING by Dr. Kenneth H. Cooper, Bantam Books, New York, 1982 awards only half the benefit points to sit-down stationary cycling (page 260) over regular cycling which includes an equal amount of uphill and downhill course (page 255). Dr. Cooper grades running better than regular cycling, but without the downhill rest inherent in regular cycling, it is certain that stand-up pedaling would be equivalent to running for cardiovascular benefits in less time.
Stand-up cycling is described in various patents such as U.S. Pat. No. 3,563,541 (Sanquist) which uses weighted free pedals as load resistance and side to side twisting motion. Also U.S. Pat. Nos. 4,519,603 and 4,477,072 by DeCloux describe stand-up cycling with free pedals in a lift mode to simmulate body lifting after the lower dead center pedal position to the other pedal in the higher position. A brake or clutch system is deployed to load or stop the lower pedal while the weight is transferred to the other pedal after the crank has passed through the dead center position. All of these stand-up cycling patents mentioned use free pedals which are free to rotate about one pivot point on the crank. Stand-up pedaling is safer when the free pedal is fully constrained to become a platform capable of providing body balance on one foot with minimum hand support.
An attempt to stabilize the pedal using a linkage is shown by Boyd in U.S. Pat. No. 1,323,004 with his mechanism for propelling bicycles. A lever is applied to the pedal to increase the mechanical advantage of the crank during the power stroke. The weight of the body is supported by the ball of the foot only and the lower most position of the pedal shows a severe incline( see Boyd FIG. 3). Boyd does not address the pedal positions necessary for for stand-up pedaling which simulate walking. Geschwender in U.S. Pat. No. 4,786,050 shows a stand-up exercise machine where elongate pedals are supported by double rotating cranks. The pedal positions shown in FIGS. 2 and 3 do not anticipate pedal inclines needed to simulate walking or running.
Parallel motion pedal constraint is shown in U.S. Pat. No. 4,643,419 (Hyde) where pulleys of the same size are coupled with a belt or chain to maintain a pedal platform horizontal or parallel to a base through a rotatable cycle of motion. Parallel pedal motion using a parallelogram linkage is shown in U.S. Pat. No. 4,708,338. Another popular stand-up exerciser is sold by Diversified Products of Opelika, Ala. as the DP Air Strider. The Air Strider provides a pedal platform constrained by two equal length cranks which are coupled by a chain riding on equal diameter sprockets giving parallel horizontal pedal motion similar to Hyde. While parallel platforms help stablize the balance of the user, the heel of the foot raises from the platform during operation when the knee is bent in the upper positions of pedal platform movement. The ankle ligaments and particularly the Achilles tendon are subjected to excessive stress when the heel is raised forcing all weight on that leg to be supported by the ball of the foot.
There is a need for an excercise machine that can be used in the stand-up mode that provides a stable pedal platform which inclines as the knee is bent thus obviating the need to raise the heel off the pedal platform whereby unwanted stress is removed from the ankle ligaments and from the Achilles tendon. There is a further need to provide a stand-up exercise machine that can be collapsed when not in use for easy stowage where floor space is scarce as in small apartments or college dorms.